To create puree, place a heaping cup of clean Oregon Grape berries into a blender or food processor and pulse a couple times until juices start to release. Do NOT over puree.

Place berry puree, lemon juice, lemon zest, sugar and eggs into a heavy bottomed saucepan. Over medium heat and whisking constantly, cook the mixture until it thickens (coats back of a spoon and whisk leaves traces in curd).

Remove from heat and pass through a fine-mesh sieve into a bowl; discard solids. Whisk butter into hot curd until well combined.

Place a sheet of parchment or plastic wrap directly on top of curd and chill until cold. Serve within one week or freeze.